EURUS'S PROFILE

I've finished every quest except, for some reason, finding all thirteen chests in the Plantation. Glancing at my completion score seems to suggest that there's one chest left on floor 1 that I seriously can't find, and I'm pretty sure I've scoured that place top to bottom. It's baffling me because nobody else seemed to be having trouble with that part. On a related note, does the prismatic claw have any use at all once you've got it?

Secondly, the map of Hornberg lists a Secret Library and three points labelled 1, 2, and 3. Those points don't seem to do anything or react in any way, though, and I haven't found any hint of how to mess with this library, if it's supposed to exist.

Finally... yeah, the other eye. Someone want to point me in the right direction? Because I'm totally lost, heh. If it's as hidden as the mask was (which I think I only found through pure luck and from spending hours looking for that last dang chest) I doubt I'll ever find it under my own power.

It's in the water spine cavern. Go to the cavern, then to the mindscape version thereof. Go all the way to the end, in the room with the lantern and the test-chest, then to the bottom left corner. There's a secret tunnel leading to a chest with it.